This invention relates generally to an electromagnetically-operated reciprocating pump to operate by means of a solenoid, and more specifically to lubrication of an electromagnetic gap between movable and fixed armatures as well as a sliding region of the movable armature in such pump.
Recently, pumps of the aforesaid type, which are driven by the driving force of a solenoid, have come to enjoy general use.
Heretofore, none of the pumps of this type has been provided with means for the positive lubrication of the sliding region of the movable armature or sliding surfaces including the outer peripheral surface of the cylindrical armature and the inner peripheral wall surface of a solenoid cylinder bore, the electromagnetic gap region between the fixed and movable armatures, and a sliding region of an intermediate member slidably disposed in a pump body and changing the pump house capacity in response to the operation of the movable armature. Such lubrication should provide cooling of those varied sliding regions as well.
Accordingly, the prior art pumps are subject to the following defects. That is, when the movable armature is attracted by the fixed armature and when the movable armature is returned by a return spring, noises and vibrations would be caused by collisions between the two armatures as well as between the movable armature and some other member. Further, in connection with this, the impact surfaces and sliding surfaces of the members should wear substantially. Since the coil temperature increases while a solenoid coil is being energized, and the solenoid coil may not positively be cooled, an excessive rise in temperature would be caused. Owing to these various factors, the conventional electromagnetically-operated pumps would not be able to perform stable electromagnetic operation, and their operating accuracy would deteriorate.
Furthermore, there is no pump of this type that includes any provision for positive and effective lubrication of an intermediate region including the intermediate member. In many cases, the intermediate region is not provided with even a means for slidingly guiding the intermediate member. Therefore, no stable reciprocating operation can be expected of such a construction.
Thus, it is impossible to obtain steady pump discharge efficiency, constituting a great obstacle to the proper operation of such fixed displacement pump, in particular.